4.3
Connected to the line supply via residual current devices (RCD)
4.3.1
Line supply connection via residual current devices
Terminology
Code
Meaning
RCD
= higher-level term
• Residual current device
• Residual current device
RCCB
• Residual current circuit breaker
• Residual current circuit breaker
• Ground-fault circuit interrupter
MRCD
• Modular residual current device
• Modular residual current device
Description
Selectively tripping, AC/DC-sensitive residual current devices (type B) can be used in addition to
the overcurrent protective devices.
WARNING
Electric shock or fire when using unsuitable residual current devices
In the case of a fault, converters can generate smooth DC fault currents, rendering type A or
type AC RCDs unusable.
• Use the recommended type B RCDs to protect converters.
• If higher-level RCDs are used, then these must also be type B devices.
You must install residual current devices (RCDs) if the line supply conditions in terms of short-
circuit power and loop impedance at the infeed point are such that if a fault occurs the installed
overcurrent protective devices will not trip within the specified time. Residual current devices
also offer preventative fire protection in the case of insulation faults, e.g. for use in high-fire-risk
working environments.
Table 4-1
Suitable RCD
Residual current devices
RCCB
Rated current
≤80 A
S220 Smart Line Modules
16 ... 24 kW
Conditions for using residual current devices
• Super-resistant (short-time-delayed) universal current-sensitive RCDs, type B
• Rated residual current 300 mA
• Separate RCD for each Line Module
Line connection and line-side power components
4.3 Connected to the line supply via residual current devices (RCD)
Booksize power units
40
Equipment Manual, 01/2022, 6SL3097-6AC30-0BP0